1. Field
The following description relates to a power supply device. The following description also relates to a power supply device that senses an AC-off state in which the driving power of the power supply device is reset, by sensing the AC-off state of an input terminal.
2. Description of Related Art
A power supply device, more specifically a switching mode power supply, refers to a device that converts and then supplies power required for driving various electronic devices such as a computer and a TV. Broadly, devices such as a transformer, a rotary converter, a mercury rectifier, and other similar devices are power supply devices. However, recently, a power converter refers to a semiconductor power converter using semiconductor hardware to act as a power converter.
For example, a power supply device may convert alternating current (AC) into direct current (DC) by Pulse Width Modulation (PWM) control.
FIG. 1 is a block diagram illustrating a power supply device by PWM control.
The power supply device illustrated in the figure in FIG. 1, a power supply device by PWM control applied for Liquid-Crystal Display (LCD) TVs, is structured to achieve high speed while minimizing power consumption.
To this end, the power supply device includes, as illustrated in FIG. 1, a bridge rectifier 10 that rectifies AC into DC, a Power Factor Correction (PFC) 20 reducing a ripple of input power, a PWM controller 30 converting power, a main board 40 supplied with the converted power, and common Light-Emitting Diode (LED) driver 50 and LCD module 60.
The power supply device that has this configuration has a function of entering into its normal operational mode, in which the driving power of the power supply device is reset, by sensing an AC-off state.
For example, when the power supply device is operating abnormally, a user can temporarily cut the AC power and then supply power again by pulling out a power plug and subsequently putting it in again. In this process, the power supply device is made to normally operate by sensing the AC-off state and then resetting the driving power for the power supply device.
However, the power supply device of FIG. 1 presents an issue in that because it senses the AC-off state by detecting only any one of two input lines for AC power, it fails to accurately sense the AC-off state. For example, the power supply device of FIG. 1 may lack the capability to properly handle the (+) or (−) half period in which AC power is supplied. Accordingly, the entire power of the device is not reset and the device remains in an abnormal state.